Help with 2 wire Trailer Brake Drum

Hey guys!

So, I'm building a 20' trailer and there seems to be some issues wiring in the electric brakes for it. We've gotten the 7 pin (I think thats what its called, its the big round connector) wired for the trailer and everything on the trailer works (All lights including marker lights, break-away brake actuator, etc) with the exception of the brakes themselves.

The drums we're using look just like the one in the picture. They're American made DEXTER brand, and I'm a little disappointed with them, we had to send one back already because studs were WAY out of position and it wouldn't mount a wheel... So they're probably not the best quality but I dont have any reason to think these are defective, so its probably just operator error.

They have the same two green wires as the one in the picture, and we're just supposed to ground one, and connect the other to the wire from the truck, right? They're both the same color so we weren't sure which was which, or if it mattered. My trailer brake controller won't recognize the trailer's existence and the brakes themselves arent engaging. What should I check? Thanks in advance.

It doesn't matter which wire goes to ground or hot, just make sure you have good ground.

Yes one wire to brake power the other to ground. Which 7 pin connector do you have? Round pins or Flat blades. There is a difference in the way they are wired. Even some flat blades are wired differently. Google trailer wiring for schematics and then check yours.

Double check the wire configuration at the plug. It can be confusing, looking at the front, looking at the back...

You can use a test light to check the truck plug, just ground the clip, start touching the terminals until the brake unit recognizes a connection. Then match that terminal with the trailer plug.

brake wires may have 2 layers of insulation. The colored PVC plastic and a clear nylon around the wire. Make sure which one you have and get the nylon stripped also so you have wire contact. Also, each brake coil is an independent circuit so it doesn't matter which wire is power or ground at each brake. When testing do NOT put full 12 volt power to the brake coils, they will fail. They may fail in less than a minute if you do. They have to be tested with a brake controller or cut back (resistor) voltage.

I have built a few trailers and I would run a ground wire all the way back to your truck plug ground. Same with your lights ground. If you don't your ball is the ground and that doesn't always work. I have seen truck plugs that brakes were on the brake pin, and others brakes were on the aux pin.

Make sure you have a ground going from the trailer frame to the ground pin on the trailer connector.

The same for the vehicle.

Some late model trucks had to have a relay and fuse installed for pulling. of a trailer.

Makes no difference which wire goes to ground or power, just one of each. I always run a dedicated power and ground wire to each brake. A cheap 2 wire extention cord is the best thing I've found to use for this. Make sure the hot wire goes to the side terminal marked blue in your plug, not the center terminal, assuming your truck is wired standard. Also make sure your break away kit is wired correctly and not breaking the circuit.

The brakes will not engage till you spin the drum(bolt the tire and wheel on the drum)

Hi 504
it won't make a difference to wiring or anything and the magnet coming live, But the axle brake left and right hand side has to be correct as well so the magnet pulls the arm the right way to activate the brakes when the trailers being pulled . I fitted a new axle to a guys dump trailer, and didn't want to pull everything apart to find out which way the arm was . so called the supplier and asked him which way the manufacturer labeled left and right,looking from front or rear to be sure the axle was mounted the right way the first time .

I need to rewire my trailers. Is this true that the wheel has to be on and have to spin the wheel for it to work? I am a definite newbie. Thanks

If you apply electricity to the magnet you can hear them hum if they are working. If they are working correctly and set right the wheel will stop instantly when turned.

The magnet wires come out onthe rear sideof the axle when properly installed.

Thanks, now I see what you were saying.